Navex details

The crash of Oxford LX745 on a nightflying cross country exercise: Calveley-Wrexham-Lichfield-Calveley occurred about 50km northeast of the intended final return destination. Can someone describe for me what is involved in a "navex" and what likely went wrong here?

Last edited by dfuller52; 25th January 2009 at 15:12.
Reason: added words

Dave,
The Met Section think that it is unlikely that the wind-flow on that night contributed significantly to the a/c being somewhat over-northeastly!!!! It was full moon (cloud cover not known) but, maybe, the Nav was concentrating too much on his charts and not enough "look-see" outside!!
A Navex was a Navigation Exercise. A route was chosen (short, or long) and the a/c had to complete the course using all the aids (or none of them!!) available at the time. Then things got harder! Not only did you have to complete the prescribed course, but in later years, you had to be over the various turning points at the right time.
This sort of thing usually sorted the men from the boys - i.e. the real Navigators from those who merely saw themselves as Directional Consultants (as we would say nowadays).
HTH
Peter Davies

Meteorology is a science; good meteorology is an art!
We might not know - but we might know who does!

Thanks Peter, this isn't looking good for my subject, who would have been doing the nav on this one. I'm thinking he got his calculations wrong and it took them near mountains when there shouldn't have been any.

When you plot their course on a map, the route they took is a mirror image of the homeward-bound leg, which suggests to me that it was a calculation error on the final heading.

They did try to contact the stations on there way around the course but something obviously went wrong on the last leg.

Thanks to the Met team. I have another one for you - involving a snowstorm - which I will put up on another thread.

Last edited by dfuller52; 25th January 2009 at 17:44.
Reason: spelling

One thing that struck me when I plotted the route and then the bearings from both Calveley and Lichfield to the crash site was that the bearing from Calveley to Shining Tor is almost a direct reciprocal of the Calveley - Wrexham leg.

What we would need would be a transcirpt of the Court of Inquiry, which we all know AHB probably have but would never give us. That would give a lot more detail about the W/T transmissions that were recorded.

As the crew consisted of a Pilot (Inst), Pilot (u/t) and Staff W/Op it would have been the u/t pilot's job to both fly and navigate with the instructor providing normal instructional guidance and the W/Op maintaining (or trying to maintain) contact with base and other local stations the radio was equipped to communicate with.

Here is a copy of the text from the back of the 1180, the original is in the hand writing of a number of people and is not that clear.

F412 Pilot’s error in descending thru cloud when he did not know his position. Failed to use “Darky”.

F412 u/c retracted when a/c hit hill
F412 “Darky” appears not to have been used. No calls heard altho’ watch maintained.
412 Wind speed had increased considerably once pilot took off & the pilot [found] from a bearing he was S of track allowed for wind [direction] change.
412 Hit high ground when descending thru cloud.

F412 Co pilot’s error in breaking clouf without knowing his posn & failing to use “Darky”. Lack of I.F. considered to have no bearing on accident. All W/T personnel to be checked for efficiency before flying. A.O.C. agrees althought says “don’t agrre lack of I.F. practice had no bearing”. Pilots must do 2hr I.F. & 2hr Link every month. A.O.C. in C. concurs."

I can understand with the wind being NE that night the aircraft ending up south of course but still the massive NE deviation is very odd.

One thing that struck me ... was that the bearing from Calveley to Shining Tor is almost a direct reciprocal of the Calveley - Wrexham leg.

Thanks Alan, that's the term I was thinking of - reciprocal. It made me think he got his math wrong and went off on the wrong vector, which sounds even more likely since, by the info on the 1180, he thought he was over the base, which he would have been if he was on the right heading. But if he had an instructor with him, how did he let it all go so far wrong?

Would anything about the accident inquiry be in my guy's file? He was RCAF.

The personnel casualty file for Ligget may well have a copy of the CoI contained within it. A lot of the Australian files have them and there is no reason to suggest that the RCAF were not also given at least one copy. With the RAAF files a copy was normally in the file of the highest ranking or most senior crew position person if there was more than one RAAF casualty from the same accident.

I would have thought the instructor, who is listed as having 788 total hours and 132 night hours (123 on the type), would have noticed such a basic navigational error, but if everything seemed to be going ok then maybe not.

Hepburn is from your 2 OTU aircraft. Got me confused for a short while. I think that explains the Nav / W/Op question as well.

This is a bit of a guess as I don't know at what height the aircraft was flying, which means I can only guess at the winds but .....

The wind was probably from the NW at about 20-25 mph, that is almost exactly along the track from Wrexham to Lichfield. Assuming the aircraft was on track and flying above cloud, it is possible it overshot Lichfield and turned onto the base track (Lichfield to Calverley) later than it should have done. This would put it flying a parallel track to the east of that intended. The track from Lichfield to Calverley is NNW, rather than NW, which means there would be a beam component to the wind effectively pushing the aircraft even further east - in other words the cumulative error resulting in the aircraft flying towards Ashbourne and the crash location.